Leading-in conductor.



E. WEINTRAUB.

LEADING-IN CONDUCTOR.

APPLICATION FILED MAY 14. 1912.

1,1 54,081 Patented Sept. 21, 1915.

Low expans/bn g/ass fntermewte g/ass WJ'TNESSEE' fAA/LNTUR UNITED STATES. PATENT OFFICE.

EZECHIEL WEINTRAUB, OF LYNN, MASSACHUSETTS, ASSIGNOR T GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

LEADING-IN CONDUCTOR.

Specification of Letters Patent.

Patented Sept. 21, 1915.

Application filed May 14, 1312. Serial No. 697,192.

To all whom it may concern:

Be it known that I, EZECIIIEL WEINTRAUB, a citizen of the United States, residing at Lynn, county of-Essex, State of Massachusetts, have invented certain new and useful Improvements in Leading-In Conductors, 0a.,

' "sten or molybdenum does not impair the which the following is a specification.

The present inventlon comprises a novel metallic seal for evacuated containers, and 1t involves the use of the metals tungsten and molybdenum for this purpose.

In the accompanying drawings, Figure 1 illustrates my invention as applied to a mercury vapor lamp consisting of a magnesium boro-silicate; and Fig. 2 illustrates a modification in which the conductors are sealed into a special form of glass.

In order to make a good vacuum-tight or hermetic seal in glass containers it is necessary that the glass and the metal have approximately the same coeflicient of expansion, that the glass should wet' the metal and thirdly, that the metal should either not oxidize during the sealing in process or that the oxid should be harmless.

Among the metals which are at all common tungsten, W, and molybdenum, M0, are the only ones that have a lower coefiicient of expansion than platinum. This is connected with the fact that the higher the melting point the lower the coeflicientof expansion. I have found that tungsten and molybdenum make a vacuum-tight seal in boro-silicate glasses having approximately the same coefiicient of expansion, say, be-

tween 3 to 5 10' and exerting what may be,

called a wetting eifect upon the metal. As an example ofsuch a glass, I mention sodium-magnesium boro-silicate, known in the market as low expansion glass which has a coefiicient of 3.5 to 4.5)(9. I have 'found thatwhen these metals are sealed in this glass that a wetting action takes place which is-equal if not superior. to the wetting. action of ordinary lead glass for platinum.

I have alsomade the discovery that the oxid of tungsten which forms on the wire during the sealing process in no way impairs the quality of the seal. This result is surprising as up to the present in the case of the various alloy substitutes proposed to replace plati: num in lead glass the formation of an oxid .has always stood in the way of a good vacu um-tight seal. In order to seal tungsten or molybdenum into bore-silicate glass, the sealing in temperature must be considerably higher as the melting point of the borosilicate is much higher than that of lead glass, and hence the tendency of the wire to oxidize must be greatly increased. It has been found, however, that oxidation of tungfinished seal. Apparently the oxid dissolves in or combines with the glass.

Fig. 1 shows a mercury arc lamp in which an open quartz tube 1, containing mercury electrodes 2, 3, is supported Within an outer tube or envelop 4. This envelop 4L consists tion, I may refer to the quartz mercury lamp which may be advantageously provided with tungsten or molybdenum seals by oining the boro-silicate glass to the quartz by means of a zone of vitreous material in which the proportion of basic constituents of the glass gradually diminish when passing from the glass to'the quartz. This construction is described more fully in my co-pending application, Serial Nos. 678,7 ll and 698,740, filed May 21, 1912. v

Seals made with the use of tungsten and molybdenum described in this application are not only cheaper than seals heretofore employed for evacuated containers, but by their use the construction of this class of apparatus may be considerably simplified.

Rectifiers, incandescent lamps, Riintgen tubes, Geissler tubes and the like can now be made not only of the bore-silicate but of other glam such as the so-called heat resisting glass or quartz by using one or a few intermediate glasses between the boro-silicate glass and the glass constituting the main body of the container, these glasses having intermediate coefficients of expansion. In the case of heatresisting glass shown in Fig. 2, only one intermediate glass is required, and even this may be omitted in some cases. The glasses of intermediate co- A in the market. Of course in the event that it should be desired to constitute the body of the container of lead glass the junctures between the boro-silicate and the lead glass may consist of three or more mixtures of lead glass and boro-silicate glass, the proportion of either ingredients in the mixtures decreasing as the juncture'with the material constituting the other ingredients is approached.

I desire by the appended claims to include a molybdenum as well as tungsten seal for evacuated containers.

What I claim as new and desire to secure by Letters Patent of the United States, is,--

'1. A container, at least one region ofwhich consists of bore-silicate glass having a coefiicient of expansion of about 3 to 5x10, and a tungsten conductor sealed therein.

2. An evacuated container, one region at least of which consists of a magnesium borosilicate, and a tungsten conductor sealed in said silicate.

3. The combination ,pf a sodium-magnesium boro-silicate glass; having a coefficient of expansion of about 3.5 to 4.5X' and a tungsten conductor sealed therein and adhering at. its surface to said glass.

In witness whereof, I have hereunto set' my hand this eleventh day of May, 1912.

EZECHIEL WEINTRAUB.

Witnesses: i

JOHN A. MCMANUS, Jr., FRANK G. Hx'rrm. 

